Process for binding together two or more layers of leather, more particularly for the manufacture of boots and shoes



Dec. 20, 1932.

M. GRUNE 1,891,412 PROC FOR BINDING TOGETHER TWO OR MORE LAYERS OF LEATHER,

HOB ARTICULARLY FOR THE MANUFACTURE OF BOOTS AND SHOES I Filed Sept. 6, 1929 Fey. 1. 5

Fag. 3. v M:

Patented Dec. 20', 1 932 tax-cam or r em r :03 nnmme 'roo'a'rm Two- 03 I03]! OF LEATHER, KOBE PAE'I'IOULABLY FOB 'l-HE IANUI'AQTUBE OF BOOTS AND SHOES Application filed September 1929, hex-k1 r...

The subjectmatter of the present inventioncomprises a proces for binding together twoormore layers of leather, more particularly for the manufacture of boots and shoes. It has already been proposed, in the :process for manufacturing boots and shoes and for the purpose of joining together several layers of leather, to use tacks or rivets made of celluloid which before being driven into the leather are dip d into a solvent, so as to render them s ciently adhesive for the purpose of jointing together the layers of leather. These known processes, however, have the disadvantage that, owing to the celluloid tacks having been previously dipped intothe solvent, the outer la ers of the celluloid tacksbecome dissolved before being driven into the leather, so that the tacks are rendered less stifi, in addition to which, owing to their adhesiveness, it is only with diflicul they can'be driven into the leather. ac-

cordance with the present invention, this dis-,

advantage is eliminated inasmuch as, before the celluloid tacks or other completely or partially soluble elastic joining media are driven into the leather, a solvent for the jointing media is applied in such a way that it really onl dissolves the outer layers of the joining me ia and, after drying, unites the latter firmly to the surrounding fibres of leather. The method of applying the solvent is as follows. The portions of leather or when a hole has previously been punched before the joining media are driven into the leather,'the hole thus previously punched is moistened with the solvent just before the jointing medium is introduced. In order to obtain as durable a joint as possible, the wires, tacks, nails, threads or the like which are used as a jointing medium can be given a large surface by being irregularly arranged, as for instance in the shape of a star. The driving of the jointing media into the layers of leather can be facilitated by providing the jointing media with a metal core, or some fibrous material or the like, so as to give them a greater-mechanical strength. In the process in accordance with the present invention, the dry jointing media can be driven easily and simply into the leather, in the that 890,766, and in Germany September 18, 1928.

same way as wooden or wire tacks, and the subsequent application of the solvent effects an intimate joint between the tacks or the like and the leather. The same effect is produced when the hole is moistened with the solvent before the tack or the ,like is driven into the leather, because in this case as wellthe pin retains its rigidity and can be driven in easily.

The drawing illustrates diagrammatically Elie process as claimed by the present inven- Figs. 1 and 2 show a plan and a. side view of a sole of a shoe and the pertinent inner sole, or upper leather, which are joined together in accordance with the present invention. belIiigs. 3 and 4 show the joint on a driving Figs. and 6 are cross sections of jointing medla suitable for the purpose of jointing. 1 If it is a (1111188131011 of manufacturing boots or shoes to w ich the present process is pref-,

erably to be applied, the shoes and boots are made essentially in accordance with the W known obsolete peg and nail process except that in Place of iron or wooden bra s, pegs made 0 celluloid, or cellon, or some similar material which is completely or partially soluble by means of aneasily drying solvent. The jointing'material can be driven into the leather in accordance with'any known method used for nailing shoes. Thus, single nails or tacks of the usual shape canbe made out of the material in question and can-then be driven into the leather with the aid of nail driving machines, or the material can be fed in the shape of endless wires and the wire cut in the known way in the finishing machine and, if need be, pointed into the shape of a nail and driven into the leather. Fi

1 and 2 show various forms of jointin me ia of this nature which are driven into t e portions of leather, namely, the sole a and the inner sole or upper leather 6, which are to be joined together. At the toe of theshoe cylindrical tacks c are assumed which are preferably cut from the wire and driven into the leather. At the middle portion of,the 1 cylindrical or cone shaped. The tacks are driven into the leather in a regular order, or, as shown in Fig. 1, in an irregular series; preferably the tacksxare given a small diameter. As soon as the tacks or pegs have been driven into the leather, the jointed places are given a coating of a solvent of the material in question of which the peg is made. Thus, where it is a question of celluloid or of cellon,

acetone or some other solvent of celluloid or cellon is used for coating purposes. The solvent penetrates into thehole-bored by the peg and at once renders the outer layer of the'wireor peg or thread adhesive. Con sequently, the leather fibres surrounding the jointing m'e'dium bind the jointing medium firmly to the leather, that is to say, the jointing mediuminserted adheres closely to the leather, thus forming an intimate bond. The jointing material can be brought to any desired degree of solution, according to the quantity of solvent used. In actual practice, however, it has been found that it is best not to go so far with the solution and always to leave a solid residue of the binding medium. By this means a very elastic joint is effected, which in no way attacks the portions of leather which are to be joined together, so that the latter need not be of any great thickness. Of course, the thickness and shape of the pegs or the like which are made of celluloid or cellon must be such as to suit the purpose intended. In the case of the finer quality ofboots and shoes very thin wires would, of course, have to be selected, whereas in the case of heavier boots and shoes a wire of larger diameter would have to be used. In the latter instance, more particularly, irregular cross sections can be used, as for example star shaped cross sections, as shown on an enlarged scale in Figs. 5 and 6. Cross sections of this kind have a comparaftively large surface, so that an intimate binding of the leather and the pegs is effected.

The jointing method described can be applied not only to the jointing of the leg of theboot to the sole, as shown in Figs. 1 and 2, but double shoes can also-be put together in this way by first of all binding the welt to the upper leather or to the inner sole, as the case may be, and then pegging the. sole to the welt and binding them together in the same not only to new shoes, but can also be used forv way. Moreover, the process can be applied resoling old boots and shoes instead of stitching them or joining them together by means.

of wooden pegs or the like. In every instance, however, the shoe is very much more elastic and pliable.

Since the binding is effected by a process of adhesion, it is not necessary to drive the jointing pins right through the parts which are to be joined together, nor, and more particularly, is it necessary, when pegging from underneath on to the inner sole, that the pins shouldpass clean through the inner sole. The jointing can be carried out. in such a way that the pins stop .short just before the upper wall of the inner sole, thus imparting to the shoe a smooth running surface. As already mentioned, any desired method of pegging or of driving in the pins or wires can be used. Wire in the shape of clamps, cramps or the like can also be used.

Figs. 3 and 4 show, finally, how the process as claimed by the present invention can be applied for the jointing of driving belts. The ends of the belts f or g are bevelled 01f, placed one on top of the other, and tacks made of celluloid or cellon are then passed through,

after which a coating of the solvent is applied. In order to hasten the adhesion of the fibres of the leather, the portions of leather can also be moistened with the solvent before and during the insertion or driving in of the nails, tacks, threads or the like, or, whenthe hole is punched first, the previously punched Since the solventshole can be so moistened. in question evaporate very rapidly and since the evaporation process is, if need be, considcurrent of air, the process can be carried out continuously, seeing that it is not necessary, as 15 the casein the known adhesive processes,

to stretch the shoes in tightly fitting presses after the solvent has been applied. The adhesion of the parts is really effected asa matter of fact by means of the pegging process.

Instead of making the tacks, wires or the like entirely of some soluble. material, they 5 is materially increased. Thus, the employ-- ment of jointing media of this kind having a core of metal or fibre is essentially suitable for the coarser kinds of boots and shoes.

The two forms of execution shown are given merely by. way of example. The process is :1 erably accelerated by means of an artificial applicable to the leather industry through- I out, that isfto-say, everywhere where there .is any question of jointlng together two or more portionsof leather.

-vent of celluloid so that it I claim:

A process for binding together layers of leather particularly for the manufacture of boots or shoes which comprises fully driving in jointin media consisting at least partially of cellulold, and then app dylisrsig a li uid sololves t e outer layers of the jointing media and binds said media after drying to the surrounding fibres of the hole of the leather into which the joint--. ing media are driven in.

n testimony whereof I aflix my si ature.

MAX GRaiflE. 

